Mozilla Fixes Firefox Crashes Linked to Intel Raptor Lake CPUs

Mozilla has released Firefox 151.0.1 on the stable Release channel, just days after Firefox 151 rolled out. The emergency update fixes a long-running crash issue affecting some systems powered by Intel Raptor Lake CPUs.

The issue mostly impacted desktop PCs and had reportedly been under investigation for nearly a year. Mozilla engineers first spotted the crashes in older Firefox Nightly builds before tracing the problem to a zlib-rs compression routine.

Firefox crash linked to Raptor Lake CPU instability

According to Mozilla, the crashes involved an incorrect 16-bit dist value that triggered index out-of-bounds failures inside the browser’s compression handling code.

While Mozilla fixed the browser-side issue in Firefox 151.0.1, the company suspects the root cause comes from known Intel Raptor Lake CPU problems tracked as RPL050 and RPL060.

RPL050 may cause one CPU core to miss the latest data written by another core. Meanwhile, RPL060 can reportedly return incorrect data during certain split-load memory operations across cache lines.

Mozilla said newer Intel 0x12c microcode updates significantly reduced the number of crashes before the browser-side fix arrived for stable users.

Heat reportedly made Firefox crashes worse

Raptor Lake processors already faced criticism over instability and overheating concerns in recent years. Mozilla engineer Gabriel Svelto previously noted that Firefox crash reports appeared to spike during summer heat waves and in warmer regions.

The comments added more attention to ongoing discussions around Raptor Lake reliability, especially for high-performance desktop systems.

Firefox 151.0.1 also fixes WebSerial problems on Windows

The update also resolves a separate Windows issue involving WebSerial.

Some websites using WebSerial to flash firmware onto devices could unexpectedly fail before the fix. Mozilla says Firefox 151.0.1 addresses the problem for affected users.

Mozilla confirms Firefox Nova redesign for 2026

Alongside the stability fixes, Mozilla officially confirmed its upcoming Firefox Nova redesign planned for 2026.

Nova is not available in the stable version of Firefox yet, but users can already test parts of the redesign in newer Firefox Nightly builds.

Firefox 151.0.1 shows how browser vendors increasingly need to work around hardware-level reliability problems, not just software bugs. The update also highlights how widespread Intel Raptor Lake instability concerns have become across gaming PCs and desktop workstations.

Via Neowin